1. Field of the Invention
The present invention relates generally to an exposure apparatus and method for manufacturing, e.g., a semiconductor device or liquid crystal display device, and is more particularly concerned with such an apparatus and method utilizing a substrate transfer device applicable to a reticle loader system or the like of the exposure apparatus.
2. Related Background Art
FIG. 7 illustrates a conventional substrate transfer apparatus. A carry by the apparatus shown in FIG. 7 is conducted as follows. The substrate storage part 1 is for storing a plurality of substrate casings 2 for encasing substrates R. A substrate R is stored in each casing. The substrate R is taken out of the substrate casing 2 by means of a carrier arm 3 and delivered to a carrier 4. The carrier 4 incorporates a prealignment mechanism. The substrate R is aligned to assume a predetermined state with respect to a carry target position. The prealignment mechanism consists of, e.g., four openable/closable pawl members. The substrate R is caught by the four pawl members, thereby effecting the prealignment. A fiducial position of the substrate R is determined by impinging surfaces of the four pawl members at that time.
The aligned substrate R is delivered to a load arm 5. Thereafter, the load arm 5 carries the substrate R to a reticle table 7. The substrate R that has completely undergone an exposure is delivered by an unload arm 6 to a carrier 4 from the reticle stage 7. Then, the substrate R is returned to a substrate storage part 1 in procedures reversed to the above-mentioned. With the operations described above, the substrate R is carried between the substrate storage part 1 and the reticle table 7. This type of apparatus is disclosed fully in Japanese Patent Application Laid Open No. 62-195143.
Another practice is that some of a plurality of arms serve as temporary standby locations.
In the prior art discussed above, other sorts of substrates R required in one lot are stored in the substrate storage part 1 while being encased in the substrate casings 2. A position of the substrate R is not fixedly held (fixed) in the substrate casing 2. Exposing involves a step of effecting a prealignment each time (herein, a step through the carrier 4). Consequently, there arises such a problem that a carry route elongates correspondingly, and it is therefore impossible to reduce a substrate replacement cycle time.
Further, in the method where some of the carrier arms serve as the temporary standby locations, if there is a large number of substrates to be repeatedly replaced, the substrates are returned to the aforementioned substrate storage part 1. Another substrate is required to be taken out of the substrate storage part 1 and carried to the temporary standby location. For this reason, a problem is caused, wherein a great number of substrates repeatedly replaceable in a short substrate replacement cycle cannot be obtained.
Moreover, when the same number of carrier arms as that of the substrates R to be replaced are disposed in side by side relationship, the arms need a large space, and the whole apparatus becomes complicated. A moving distance of the carrier arm increases when loading and unloading the substrate R. This results in a decline in throughput of carrying the substrates. Under such circumstances, there exists a problem in which the number of the carrier arms cannot be increased.
It is an object of the present invention to provide an apparatus and method that are capable of reducing a replacement cycle time with an omission of a prealignment step as well as shortening a carry route for replacement of a substrate.
It is another object of the present invention to provide an apparatus and method that are capable of replacing a plurality of substrates in a short replacement cycle time.
It is still another object of the present invention to provide an apparatus and method that are capable of carrying a substrate with no positional deviation.
According to a first aspect of the invention, there is provided an apparatus having: a substrate storage part for storing substrate casings that encase substrates; and a carrier system for carrying a substrate to a substrate stage from the substrate storage part, the apparatus comprising: a first carrier means for carrying a substrate to a first substrate carry position from the substrate storage part; a temporary storage unit incorporating a holding mechanism for individually adsorptively holding the substrate by vacuum in a predetermined state and provided between the first substrate carry position and the substrate stage; and a second carrier means capable of carrying the substrate to the substrate stage from the first carry position and also carrying the substrate between the temporary storage unit and the substrate stage.
According to a second aspect of the invention, there is provided a substrate carrying apparatus for carrying a substrate to a substrate stage, comprising: a substrate storage part incorporating a holding mechanism for individually adsorptively holding the substrate by vacuum in a predetermined state; and a carrier means, capable of carrying the substrate to the substrate stage from the substrate storage part while adsorptively holding the substrate by vacuum, for carrying the substrate while keeping a position of the substrate on the substrate stage.
According to a third aspect of the invention, there is provided a substrate carrying method of carrying a substrate between a substrate storage part for storing the substrate and a substrate stage for locating the substrate in a predetermined fiducial position, the method comprising: a first step of carrying a substrate to the substrate storage part from the substrate stage; a second step of carrying the substrate to the substrate stage from the substrate storage part; a third step of obtaining an offset quantity on a position of the substrate on the substrate stage from the fiducial position on the basis of the first and second steps; and a fourth step of altering a relative position of the substrate stage to the carrier means in accordance with the offset quantity before the substrate is carried to the substrate stage.
The temporary storage unit is advantageously installed in relatively close proximity to a carry target position separately from the substrate storage part, whereby a carry time can be reduced.
Further, each substrate can be directly adsorptively held in the temporary storage unit. Therefore, the substrate that has been once aligned has no positional deviation. For this reason, the substrate can be carried between the temporary storage unit and the substrate stage without passing through the prealignment step.
In addition, if the storage part incorporates a partial air-conditioning function, a clean storage with no dust can be attained.
According to a fourth aspect of the present invention, there is provided a substrate transfer apparatus comprising a temporary storage device, for temporarily storing the substrate, so supported as to be movable in a direction (Z-direction) intersecting the surface of the substrate stage. The substrate transfer apparatus further comprises a substrate holding unit for adsorptively holding the substrate and a rotary arm device, for rotating this substrate holding unit, including a rotary up-and-down member for rotating this substrate holding unit and moving the substrate holding unit in the direction Intersecting the surface of the substrate stage. The substrate is thereby transferred and received between the temporary storage device and the substrate stage through the rotary arm device.
In this case, the rotary arm device is provided with two substrate holding units for holding the substrate. Desirably, each of these two substrate holding units has a pair of substrate adsorptive members opened and closed along the substrate to be held.
According to a fifth aspect of the present invention, a substrate transfer apparatus comprises a substrate transfer unit for transferring and receiving the substrate with respect to a substrate storage device and a temporary storage device, for temporarily storing the substrate between this substrate transfer unit and the substrate stage, so supported as to be movable in a direction (Z-direction) intersecting the surface of the substrate stage. The substrate transfer apparatus further comprises a rotary arm device including a substrate holding member for adsorptively holding the substrate and a rotary up-and-down member for rotating this substrate holding member and thus moving the substrate holding member in the direction intersecting the surface of the substrate stage. The substrate is thereby transferred and received between the temporary storage device and the substrate stage through the rotary arm device.
In this case, the substrate storage device and the substrate transfer unit are mounted on a first base, while the temporary storage device and the substrate stage are mounted on a second base different from the first base. It is desirable that there be provided a substrate locating unit for locating the substrate when transferring the substrate to the temporary storage device from the substrate transfer unit.
Provided further is a vibration detecting unit for detecting a deviation quantity between the first base and the second base. When the positional deviation quantity detected by this vibration detecting unit exceeds a predetermined allowable value, it is desirable that the transfer of the substrate from the substrate transfer unit to the temporary storage device be stopped.
In the substrate transfer apparatus according to the fourth aspect of the present invention described above, the substrate is transferred and received between the temporary storage device and the substrate stage by use of the rotary arm device. In this instance, a desired substrate is replaced between the temporary storage device and the substrate stage with a rotation of the substrate holding member of the rotary arm device as well as with an up-and-down movement of the temporary storage device. A standby position of the substrate is therefore substantially the same as a position of the temporary storage device. Further, the substrate is replaced by making use of the rotation, and, hence, the transfer path of the substrate is short, with the result that the replacing speed of the substrate is quite high.
Moreover, there are provided two substrate holding members each having a pair of openable/closable substrate adsorptive members. In this case, when the substrate is used inwardly of, e.g., one pair of substrate adsorptive members, the other pair of substrate adsorptive members are set in an opened state. Besides, preparation for taking out the substrate that is to be used next is finished simply by moving the temporary storage device to a take-out position of the next substrate. Accordingly, the time for preparing the substrate employed next is remarkably reduced.
In the substrate transfer apparatus according to the fifth aspect of the present invention, the substrate is transferred and received between the temporary storage device and the substrate stage by use of the rotary arm device, and, therefore, the transfer path of the substrate is short, and the transfer speed of the substrate is high, whereby the speed of replacing the substrate is quite high.
In addition, the substrate storage device and the substrate transfer unit are mounted on the first base, while the temporary storage device and the substrate stage are mounted on the second base different from the first base. Provided also is a substrate locating unit for locating the substrate when transferring the substrate from the substrate transfer unit to the temporary storage device. In this case, the vibrations on the side of the substrate transfer unit are not transmitted to the substrate stage. Moreover, the locating of the substrate is conducted by the substrate locating unit, and hence the prealignment of the substrate on the substrate stage can be omitted.
Provided further is a vibration detecting unit for detecting the deviation quantity between the first base and the second base. When the positional deviation quantity detected by this vibration detecting unit exceeds a predetermined allowable value, the transfer of the substrate from the substrate transfer unit to the temporary storage device is stopped. In this case, the substrate is transferred to the temporary storage device in a state where the deviation quantity from the position located by the substrate locating unit is lessened, and therefore the rough locating can be omitted on the side of the temporary storage device.
Other objects, aspects, and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments in conjunction with the accompanying drawings. For example, it will be seen that another aspect involves an exposure method which exposes a pattern on a mask stage onto a substrate, wherein the mask is transferred to the mask stage by a transfer device, and the transfer device is moved to a position at which it does not hinder an exposure.